Abstract: This invention concerns compounds of formula the N-oxide forms, the pharmaceutically acceptable acid addition salts and stereochemically isomeric forms thereof, wherein R1 is hydrogen, C1-6alkyl, C1-6alkyloxy, C1-6alkylthio, amino, mono- or di(C1-6alkyl)amino, Ar1, Ar1—NH—, C3-6cycloalkyl, hydroxymethyl or benzyloxymethyl; R2 and R3 are hydrogen, or taken together may form a bivalent radical of formula —CH═CH—CH═CH—; R4, R5 and R6 are each independently selected from hydrogen, halo, C1-6alkyl, C1-6alkyloxy, trifluoromethyl, nitro, amino, cyano, azido, C1-6alkyloxyC1-6alkyl, C1-6alkylthio, C1-6alkyloxycarbonyl or Het1; or when R4 and R5 are adjacent to each other they may be taken together to form a radical of formula —CH═CH—CH═CH—; A is a bivalent radical of formula NR7, NR7-Alk1-X-, NR7-Alk1-X-Alk2-, O-Alk1-X-, O-Alk1-X-Alk2- or S-Alk1-X-; wherein X is a direct bond, —O—, —S—, C═O, —NR8&md